title: Effect of surface area ratios and bacteria on electrochemical behavior of galvanically coupled titanium.
abstract: OBJECTIVE
  This study aimed to investigate the electrochemical behavior of commercially pure titanium (grade II) coupled with type IV gold alloy and nickel-chromium alloy at different surface area ratios in 3 different electrolytes.
  
  
  METHODS
  Titanium was coupled with gold (Ti/Au) and nickel-chromium (Ti/Ni-Cr). For each couple, 9 surface area ratios between titanium and gold or nickel-chromium were prepared. The electrolytes used were 1% lactic acid, tryptic soy broth media, and Streptococcus mutans culture supernatant. The corrosion polarization curves were obtained, and average values of corrosion potential and corrosion current density were calculated.
  
  
  RESULTS
  Both Ti/Au and Ti/Ni-Cr were affected by surface area ratios and different electrolytes, showing the least corrosion rate when the ratio was 1:1 and when the lactic acid was used as an electrolyte.
  
  
  CONCLUSIONS
  The greater the difference in surface area between titanium and restorative materials, the more corrosive behavior the materials show. The existence of bacteria such as S mutans may aggravate corrosive behavior between different metals.
authors.affiliation: Department of Biologic and Materials Sciences, Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, Michigan 48109-1078, USA. ilwoong@umich.edu
authors.forename: Ilwoong
authors.initials: I
authors.lastname: Koh
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Oshida
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Andres
authors.forename: Richard L
authors.initials: RL
authors.lastname: Gregory
mesh_terms: D001422:Bacterial Adhesion; D002858:Chromium Alloys / Q000737:chemistry*; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D015921:Dental Implants; D004563:Electrochemistry; D004570:Electrogalvanism, Intraoral; D004573:Electrolytes / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry*; D008422:Materials Testing; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D015921:Dental Implants; D004573:Electrolytes; D006047:Gold Alloys; D014025:Titanium